Searchlight



March 26, 1940. J. c. SAVAGE smacnmenw Filed March 24, 1937 5Sheets-Sheet 1 Fig.1. 5

March 26, 1940. J. c. SAVAGE smncamem Filed March 24, 1937 5Sheets-Sheet2 March 26, 1940. J. c. SAVAGE SEARCHLIGHT Filed March 24, 1937 5Sheets-Sheet 5 March 26, 1940. J, c. SAVAGE SEARCHLIGHT Filed larch 24.1937 5 Sheets-Sheet 4 March 26, 1940. J c SAVAGE 2,194,836

SEARCHLIGHT Filed March 24, 1937 5 Sheets-Sheet 5 Patented Mar. 26, 1940SEAROHLIGHT John Clifford Savage, Hendon, London, England ApplicationMarch 24, 1937, Serial No. 132,837

In Great Britain March 26, 1936 4 Claims.

The present invention relates to searchlights and has for its chiefobject to provide an improved searchlight so constructed as to enable alarge area to be rapidly and thoroughly scanned by the light beamwithout appreciable reduction in the intensity of the light per unitarea.

Another object of the present invention is to provide a searchlight thelight beam from whichis capable of being spread or diverged linearlyinaplane at right angles to the optical axis of the projector and alsoof being traversed continuously, prefer-- ably to variable extents, in adirection parallel to the optical axis of the projector.

A still further object of the present invention is to provideasearchlight whose light beam is capable of being continuously traversedand automatically spread or diverged linearly to an extent depending onthe extent of the traversing movement.

Further objects and advantages of the present invention will becomeapparent from the accompanying detailed description of a preferredembodiment thereof with reference to the accompanying drawings in which:

Fig. 1 is a view illustrative of the purpose of the present invention;

Fig. 2 is a view in side elevation of a motor road vehicle equipped witha searchlight according to the present invention;

Fig. 3 is an end elevation of the motor road vehicle shown in Fig. 2;

Fig. 4 is a plan view of the mirror mosaic or assembly employed in asearchlight according to the present invention;

Fig. 5 is a view in side elevation of the mirror mosaic or assembly;

Fig. 6 is a cross sectional view on the line A--B of Fig. 5;

Fig. 7 is a view in side elevation of means for traversing the mirrormosaic or assembly.

Searchlights as usually constructed project, generally speaking, aparallel or substantially parallel beam of light, the cross sectionalarea of which at any distance from the projector is approximatelycircular and of more or less limited dimensions: consequently much timeis required to scan a given area with the beam and there is considerablelikelihood of the object which it is desired to find and illuminateremaining unilluminated even if it maintains a perfectly straight andlevel course, and where, as in the case of aircraft, the object iscapable not only of considerable speed but also of being manoeuvred 55in three dimensions to avoid the beam, the chances ent invention isconstructed in such a manner that the light beam is capable of, beingspread or diverged linearly, preferably to variable extents 15 andwithout substantial reduction of light intensity per unit area, in aplane normal to the op- 'tical axis of the projector, that is to say, sothat it has an elongated rectangular, instead of a substantiallycircular, form in cross section, and '2 by traversing such a spread ordiverged light beam backwards and forwards a large area can be rapidlyscanned.

In Fig. 1 the circular area a represents an area on a screen, such as acloud layer, illuminated 25 by a searchlight beam of circular crosssectional form, and the elongated rectangulararea 1) represents an areailluminated by the same beam when spread or diverged linearly according.to the present invention. It will be apparent that 30 by, rocking ortraversing the linearly spread or diverged beam an area, such asrepresented at 0, can be scanned very much more rapidly than the samearea could be scanned by the beam producing the more limited illuminatedarea a. 5

The extent of the linear spread or divergence of the beam of thesearchlight according to the present invention is preferably capable ofbeing varied as desired and d and e represent areas 7 which could bescanned by the beam when lin- 40 early spread or diverged to a lesserextent.

As will be appreciated the maximum permissible linear spread ordivergence of the beam should be such that sufiicient intensity ofillumination is always available.

A further feature of the present invention resides in continuouslylooking or traversing the beam when linearly spread or diverged.Preferably the degree of linear spread or divergence is automaticallyadjusted to correspond with the 50 extent of the rocking or traversingmovement, that is to'say, as the linear spread'or divergence increasesthe extent of the traversing movement is automatically increased andvice versa.

Referring to Figs. 2-7 inclusive of the accompanying drawings, 1 is aprojector comprising a source of light 2, shown as an electric arelight, located at or near the focus of a curvedfor example aparabolic-reflector 3, arranged to project a substantially parallellight beam in a horizontal direction on to a mirror mosaic or assembly lsupported on a frame 5 which occupies an inclined cross sectional areaof the beam and is mounted for pivotal or rocking movement about an axis6 lying in a plane passing through the principal axis of the projector Iby means of trunnions i which cooperate with bearings 8 on supports 9carried at opposite sides of the cylindrical casing ill. The cylindricalcasing l0 has an aperture i l through which the beam reflected from themirror mosaic 4 emerges. The casing Ill is supported for rotation aboutits longitudinal axis upon end members i2 and I3 having rollers it whichengage in suitable runways [5 on the casing it.

The projector l, casing It and appurtenant parts are carried upon aplatform Hi which is mounted upon vehicle I"? for rotation about avertical axis i8. For this purpose an electric motor l9 carried by theplatform [6 drives a gear '28 which is in engagement with a gear 2!rigidly secured to the vehicle ii.

The platform i6 also carries an electric motor 22 which drives throughthe gearing 23, 26 and other gearing not shown a pulley 25 adapted torotate the casing it about its longitudinal axis through suitable belttype gearing 2%). Locking devices 21, 28 adapted for engagement withfixed parts of the vehicle are provided at each end of the platform l6for normally holding the platform it with its longitudinal axis in linewith the longitudinal axis of the vehicle.

The mirror mosaic l comprises an assembly of separate reflectors some ofwhich, as 29, are fixed upon the frame Ii and others of which, as 38,are mounted upon the frame 5 so as to be capable of individual rockingor tilting movement for the purpose of spreading or diverging thereflected beam in the manner hereinbefore referred to. As shown therockable or tiltable reflectors 39 are rectangular in form and aredisposed on opposite sides of a plane passing through the principal axisof the projector l and normal to the rocking axis '3 of the frame 5. Thereflectors 33 are further disposed with their longitudinal axes parallelto the rocking axis 6 of the frame 5 and to permit individual rocking ortilting movement they are secured, as by screws or the like, toelements, 31m hinged or otherwise rotatably connected to members Sill)forming part of the frame 5, the hinging or rocking axes 3! being soarranged that they are parallel to the principal axis of the projectorwhen the frame 5 is arranged at 45 to the principal axis of theprojector.

For effecting rocking or tilting movement of the reflectors 38 eachreflector is provided with a rod 31a which extends parallel to thelongitudinal axis thereof, and bears in the respective element 39a andalso in a block or the like 3H) secured to the reflector as by screws orthe like. The inner end of each rod 3 to engages in an inclined slot 32in a guide member 320. attached to beam 33 forming part of the frame 5and also in a cooperating slot extending longitudinally of a control bar5* which is pivoted at one end to the frame 5 at 3t. With thisconstruction movement of the control bar 35 about its pivot 36 effectstilting of the reflectors 30 about their axes 3|, the amount of thetilting movement of the respective reflectors depending upon theirdistance from the pivot 36 of the control bar 35.

In the embodiment of the invention shown the frame 5 is adapted to berocked continuously about its axis 6 for the purpose of continuouslytraversing the beam by an electric motor 31 through mechanism designedto permit of adjustment for the purpose of enabling the extent of therocking movement, and consequently the traverse of the beam, to bevaried as desired. This mechanism may conveniently comprise a link 38pivotally connected at one end to the frame 5 at a distance from itsrocking axis 6 and pivotally connected at its other end to a slide ortrolley 39 longitudinally movable with respect to a frame member 49pivoted at 4| on a support 42 and which can be rocked about its pivot bya link 53, one end of which is connected to a crank 4 on the shaft ofthe motor 31. The slide 39 is adapted to be moved along the pivotedframe member it) by means of an electric motor 45 which drives a shaft46 engaging the trolley 39 through suitable reduction gearing ll and aslipping clutch 48. The slide or trolley 39 conveniently has rollers itwhich engage the frame member to facilitate its movement. The extent ofthe rocking or traversing movement imparted to the frame 5 depends uponthe position the slide or trolley 39 occupies along the frame member.When the axis of the pivotal connection of the link 38 to the trolley 39is coincident with the axis of the pivot H no rocking movement isimparted to the frame 5. On the other hand, as the distance betweenthese two pivotal axes increases the extent of the rocking movement ofthe frame 5 increases.

For simultaneously and automatically controlling the spread ordivergence of the beam and its traversing movement, the slide or trolley39 is connected with the control bar 35 and in the embodiment shown theslide or trolley 39 is connected by means of Bowden cables 5D, 54 to theopposite ends of a differential lever 52 pivoted beneath the frame 5,other Bowden cables 53, 5 being connected between th lever 52 and thecontrol bar 35 as shown. By this arrangement any movement of the slideor trolley 39 produces a corresponding movement of the control bar 35and consequently of the tiltable reflectors 3E! and thereby enables boththe traversing movement and the linear spread or divergence of the beamto be varied by operation of a single control.

Any suitable form of reflector, such as a mirrored glass or highly poished metal, may be used, and it will be understood that the particularmode of producing the tilting movement may be varied in any desiredmanner providing it is such as to enable the beam to be linear spread ordiverged in a plane normal to the optical axis of the projector. Forexample instead of the slots and 3d suitable surfaces may be providedwithwhich the ends of rods 31a are maintained in engagement by means ofhelical springs each secured at one end to a corresponding rod and atthe other end to the frame 5. Such an arrangement as last describedenables the central fixed reflector '29 to be dispensed with.

Although the Searchlight has been shown and described herein as mountedupon a motor road vehicle it may obviously be mounted upon any otherform of vehicle or in a fixed position. When mounted upon a vehicle thepropelling engine may be employed when the searchlight is being used todrive a dynamo for supplying the purposes decross sectional area of saidbeam, a pivotal mounting for said frame lying in a plane passing throughthe principal axis of the projector, a plurality of mirrors each mountedupon said frame for angular adjustment about an axis parallel to theprincipal axis of the projector when the frame is at 45 to saidprincipal axis, means for rocking said frame about its pivotal axis, andmeans coordinating the extent of said rocking movement with the angularadjustment of said mirrors.

2. A Searchlight comprising a projector adapted to project asubstantially parallel beam of light, a frame mounted to occupy aninclined cross sectional area of said beam and pivoted about an axislying in a plane passing through the principal axis of the projector, aplurality of mirrors each mounted on said frame for angular adjustmentabout an axis parallel to the principal axis of the projector when theframe is at 45 to said principal axis, means for simultaneouslyangularly adjusting said mirrors to different extents about theirpivotal axes, means for continuously rocking said frame, means for varying, the extent of said rocking movement, and means co-ordinating theextent of the rocking movement of the frame with the degree of spread ofthe beam. g

3. A searchlight comprising a projector adapted to project asubstantially parallel beam of light, an assemblage of mirrors mountedto occupy an inclined cross sectional area of saidbeam and eachangularly adjustable to permit spreading of the beam linearly, means forcontinuously rocking said assemblage to and fro, means for varying theextent of said rocking movement, means for simultaneously adjusting theangularity of said mirrors, and means interconnecting said mirroradjusting means and said assemblage rocking movement varying meanswhereby said beam is spread linearly proportionately to the extent ofits traversing movement.

' 4-. A Searchlight comprising-a projector adapted to project asubstantially parallel beam of light, an assemblage of mirrors mountedas a whole to occupy an inclined cross sectional area of saidbeam andangularly adjustable with respect to one another for the purpose ofspreading said beam linearly, a pivotal mounting for said assemblage, acontrol bar for simultaneously angularly adjusting said mirrors, amember rockable about a fixed pivot, a trolley slidable lengthwise ofsaid member, a link connected to said assemblage at a distance from itspivotal axis and also to saidtrolley, andmeans connecting said trolleyand said control bar whereby movement of said trolleycauses aproportional movement of said control bar.

JOHN CLIFFORD SAVAGE.

